1. Field of the Invention
The present invention relates generally to gas turbine engines and, more particularly, to an auxiliary refrigerated air system on an aircraft employing input air, from a suitable source such as air bled from the turbine engine compressor, and air recirculated within the system.
2. Description of the Prior Art
The requirement has existed heretofore for aircraft turbine engine systems to produce cool air for use in aircraft support systems such as for cabin environmental control and avionic cooling. In one conventional aircraft support system, fresh air is initially obtained by bleeding air from one or more of the aircraft's engines and then conditioned before introduction into the pressurized fuselage of the aircraft. In this support system as described and illustrated in U.S. Pat. No. 4,262,495 to Gupta et al, the bleed air is conditioned by the coordinated operation of a power turbine, a recirculation air compressor, an air filter and an air-to-air heat exchanger of the system. Another known aircraft support system utilizing engine bleed air to heat the engine fuel is described and illustrated in U.S. Pat. No. 4,404,793 to Coffinberry.
The air quantity and air temperature requirements of conventional aircraft support systems have been relatively modest heretofore. The cooling requirements of future turbine engine systems will likely demand significantly increased quantities of air at substantially lower temperatures. One such example is in the area of superconductors. Emerging superconductor technology may find application in future turbine engine systems for power generation, as one example, or in magnetic bearings, as a second example. Although the technology of superconductors has made major advances in elevating the temperature at which they function, a cold or refrigerated temperature by normal standards is still required.
Conventional cold or refrigerated air systems used on aircraft heretofore do not provide air in sufficient quantities and at sufficiently low temperatures to meet the anticipated cooling requirements of future turbine engine systems. Consequently, a need exists for a refrigerated air system which will meet forecasted future requirements.